It's October 31st, arguably one of the greatest days of the year (*maybe* second to the winter holiday...which reminds me, as a child I really, really loved the film "The Nightmare Before Christmas" because it combines BOTH EVENTS). Lots of traditions and superstitions are alive and well on All Hallow's Eve, including a staunch appreciation for, or rigid avoidance of, the ever impressive black cat.

Salem, the OG black cat of Halloween from Sabrina the Teenage Witch.

Having a black (indoor) cat myself, I'm pro-melanistic-feline, and so are many other people. So much so, in fact, that they spend a lot of time talking about wild black cats! However, there are several species for which there is zero evidence of melanism occurring in the wild (see this guest post by ecologist t Dr. Michelle LaRue on why melanistic cougars are not a thing). This is primarily owed to genetics and evolution. For example, in species like the rock pocket mouse, a light-colored mouse living on light-colored lava rock in the southwestern US, some populations exhibit mutations in a pigmentation gene called Mc1r, and these changes are responsible for the black phenotype. The role of genetics in adaptive evolution- the selection of beneficial alleles given the environment- is traceable in several taxa, including the pepper moth, a European species that exhibited near-total population melanism in under 10 generations in response to industrial pollution (ash, sulfur on trees) in the UK. In most cases, melanism is a recessive trait, meaning both parents must carry the mutation on a pigmentation gene in order for offspring to inherit and exhibit the phenotype of a recessive genotpye (think big A and little a from genetics: AA, Aa, and aa, where an animal must have the aa genotype to be melanistic). For wild cats (your terror of a housecat not included), melanism can occur, but in which species?

Of the 38 species of wild cats, 11 exhibit melanistic coat coloration polymorphism. Surprisingly, there are at least 4 independent genetic origins of melanism in Felidae! Natural selection mediates coat melanism in these species: the jaguar, leopard, jaguarundi, bobcat, serval, Geoffroy's cat, Oncilla, Pampas cat, kodkod, jungle cat, and Asiatic golden cat. While some of these species are not widely known, the term "black panther" (which is actually not a term for a specific species!) is most notably used in reference to a black jaguar or black leopard. Other than National Black Cat Day, I see no better day than Halloween to introduce a few of our world's melanistic wild cats:

Melanistic jaguar. In the right light, you can still see the rosette-shaped spots! Photo by Ron Singer.

Pictured above, the jaguar is the largest of South America's big cats, and black individuals are common in zoos and the pet trade. However, the frequency of occurrence of this color polymorphism is not well understood in wild populations. This cool study successfully used fecal DNA to map wild melanistic jaguars in Brazil using the amino acid deletions in the Mc1r gene.

A melanistic leopard stands in stark contrast to the normal phenotype. Taken at the Kali Tiger Reserve in India by the National Tiger Conservation Authority.

Like the jaguar, the leopard exhibits melanism as a recessive trait. For many wild populations, the frequency of occurrence for melanism can become prominent, but this trait is not expected to be fixed within populations due to its Mendelian inheritance (ie, its recessive nature). However, this study found near-fixation (meaning that melanism is the only variant of the pigmentation allele) on the Malay Peninsula. Cool!

This melanistic bobcat was legally trapped in 2016 in New Brunswick, Canada.

Bobcats, one of my favorite species, also exhibit melanism. Few records exist in the continental US, most of which are in southern Florida. Black bobcats have been recorded by fur trappers in New Brunswick, Canada since at least 1983. This is cool, because it means that the polymorphism has persisted across several generations in this area!

A black serval seen in Kenya. Photo by Sergio Pitamitz

The serval is a medium-sized wild cat distributed across much of southern Africa. These cats share a phylogenetic history with caracals, Bay cats, and Asiatic golden cats (another species that exhibits melanism). I worked with captive servals many years ago at Carolina Tiger Rescue- these cats can jump over ten feet in the air! Melanism is rare in this species, and two white servals exist in captivity in Florida.

A fellow graduate student in my lab, Hariyo Wibisono, and one of my mentors, Dr. Jennifer McCarthy, documented a melanistic marbled cat in Sumatra, Indonesia, in 2010. The 12th cat! Check this out:

Humans are fascinated with black color morphs. Wild cats are elusive and rare, which makes melanistic individuals all the more exciting. Melanistic cats are great examples of the diversity and impact of genetics and the role polymorphism plays in natural selection and evolution. The next time you hear someone talk about a "black panther," you can now tell them which one they likely saw (your terror of a housecat included)!

Disclaimer 1: Like any wild cat, never approach a melanistic cat on Halloween, or on any other day for that matter, because wild cats are not pets, and because you could bleed a lot.

Disclaimer 2: If you have a black cat, consider keeping him or her inside tonight (and every day, because this), as some people are unkind to black cats on Halloween.

Nachman, M., Hoekstra, H., and S. D'Agostino. 2003. The Genetic Basis of Adaptive Melanism in Pocket Mice. Proceedings of the National Academy of Sciences of the United States of America 100: 5268-5273.